Closed cartons or containers, particularly those used in the fast food industry wherein only a single use is contemplated, are conventionally formed to not only accommodate the particular goods therein, but also to in themselves provide a practical and economically feasible product
The carton must be able to not only close and lock in a positive manner, but also easily open for access to the carton contents. An example of such a carton, using interengaging projecting detents and detent receiving slits will be noted in applicant's prior U.S. Pat. No. 4,877,178, issued Oct. 31, 1989.
Known fast food cartons, whether folded from paperboard blanks or of molded paperboard or synthetic resinous materials, are, for ease of storage and shipment, designed for compact nesting. While this ability to nest significantly contributes to the practicability of shipping the assembled cartons to the user, as opposed to requiring the user to assemble the cartons at the point of use, in those instances wherein the tray and cover are completely separable components, note for example FIGS. 5-9 of U.S. Pat. No. 4,877,178, the user must be provided with a stock of both types of components. This in turn requires that the user of the cartons maintain an equal supply of both components and provide accessibility to both supplies. As can be appreciated, particularly in a limited space, this will require substantially double storage capability.
The conventional two part carton, in providing for an interlock between the tray and cover, form each of these components with complementary although different interlocking means, normally projections or tabs on one component and tab receiving recesses, slits or notches on the companion component.
The provision of two distinct components respectively defining the tray and cover of the cartons also necessitates substantial expense in that separate cutting dies are required and time must be allocated to produce two separate forms of components. In addition, there must be coordination in the production of the two sets of components and in the storage and shipping of the separate components.
Another problem encountered in providing fast food cartons in particular is the necessity for providing substantial structural stability at minimal cost both in materials and in production. One area of weakness normally found in such cartons is at the internal slits, notches or openings through the material of the carton in either or both of the tray and lid for cooperation with complementary projections on the second component. Such openings not only weaken the material and provide for potential tear areas, but also tend to interrupt areas on which printed copy or indicia appears. In addition, the actual formation of such openings and the removal of the cut material from the blank at the time of forming is an inherently complex procedure.